1996/97 Mars Sketch (7)
from CMO #205 (25 July 1998)


-- Elysium in March 1997 --


Japanese here


W

e here review the Japanese observations of Elysium in March 1997 when the Martian season was near 090Ls. As reported in CMO No187 p2033 the region was impressively whitish bright in the afternoon side. From 7 Mar (087Ls) to 13 Mar (090Ls) there were obtained a number of observations (every forty minutes) in Japan and we here record the data.
  As a good example, we first introduce the observations by ISHADOH (Id) made on 10 March. His observations started from 13:20GMT and ended at 18:10GMT on the night and were made in the following way:

Id-076D 10 Mar (089Ls) ω=231W

Id-077D 10 Mar (089Ls) ω=241W

Id-078D 10 Mar (089Ls) ω=250W

Id-079D 10 Mar (089Ls) ω=260W

Id-080D 10 Mar (089Ls) ω=270W

Id-081D 10 Mar (089Ls) ω=280W

Id-082D 10 Mar (089Ls) ω=289W

Id-083D 10 Mar (089Ls) ω=302W

 

  Elysium was apparent from the outset (Id-076D), but it became very evident from around Id-079D. In Id-082D, Elysium was near the terminator and nearly vanished in Id-083D. Id made also at ω=300W on 9 Mar where the situation was the same. On 10 Mar the phase angle was 07, and Elysium was at around 4 o'clock local time when Id-080D (ω=270W) was made.
  Elysium Mons described by Id became whitish bright in the deep afternoon and hence this phenomenon was caused by such a white orographic cloud as reviewed in Mars Sketch (3) in No 201.


Fig. ISHADOH's drawing (Id-080D) on 10 Mar 1997 (089Ls)
at ω=270W showing a very whitish bright cloud at Elysium Mons

  At Fukui, NAKAJIMA (Nj) made a similar continual observations of the afternoon Elysium on 8 March (088Ls). On the day he witnessed that Elysium was whitish bright enough at ω=244W. On the following day on 9 Mar (088Ls), Nj however saw the off-white tint remain at the region of Elysium at ω=235W. MINAMI (Mn) on 9 Mar detected Elysium Mons through O56 atω=220W while it became well whitish at ω=240W and very brilliant at ω=260W. Nj and Mn watched the region from 7 Mar to 11 Mar as follows:

Mn-332D 7 Mar (087Ls) ω=248W

Nj-093D 7 Mar (087Ls) ω=252W

Mn-333D 7 Mar (087Ls) ω=257W

Nj-094D 7 Mar (087Ls) ω=262W

Mn-334D 7 Mar (087Ls) ω=267W

Nj-095D 7 Mar (087Ls) ω=272W

Mn-335D 7 Mar (087Ls) ω=277W

Nj-096D 7 Mar (087Ls) ω=282W

Nj-097D 8 Mar (088Ls) ω=224W

Nj-098D 8 Mar (088Ls) ω=234W

Nj-099D 8 Mar (088Ls) ω=244W

Nj-100D 8 Mar (088Ls) ω=253W

Nj-101D 8 Mar (088Ls) ω=263W

Nj-102D 8 Mar (088Ls) ω=273W

Nj-103D 9 Mar (089Ls) ω=215W

Mn-336D 9 Mar (089Ls) ω=220W

Nj-104D 9 Mar (089Ls) ω=225W

Mn-337D 9 Mar (089Ls) ω=230W

Nj-105D 9 Mar (089Ls) ω=235W

Mn-338D 9 Mar (089Ls) ω=240W

Nj-106D 9 Mar (089Ls) ω=245W

Mn-339D 9 Mar (089Ls) ω=250W

Nj-107D 9 Mar (089Ls) ω=255W

Mn-340D 9 Mar (089Ls) ω=259W

Mn-341D 9 Mar (089Ls) ω=272W

Mn-342D 9 Mar (089Ls) ω=281W

Mn-343D 9 Mar (089Ls) ω=291W

Mn-344D 9 Mar (089Ls) ω=301W

Mn-348D 11 Mar (089Ls) ω=203W

Mn-349D 11 Mar (089Ls) ω=230W

Mn-350D 11 Mar (089Ls) ω=240W

Mn-351D 11 Mar (089Ls) ω=249W

Mn-352D 11 Mar (089Ls) ω=259W

Mn-353D 11 Mar (089Ls) ω=271W

Mn-354D 11 Mar (089Ls) ω=281W

Mn-355D 11 Mar (089Ls) ω=291W

Nj-110D 11 Mar (089Ls) ω=295W

Mn-356D 11 Mar (089Ls) ω=300W

Nj-111D 11 Mar (089Ls) ω=305W

Mn-357D 11 Mar (089Ls) ω=310W

Nj-112D 11 Mar (089Ls) ω=315W

 

We also have other observations among which the following are included:

 

Mo-054CCD 11 Mar (089Ls) ω=250W

Id-084D 11 Mar (089Ls) ω=251W

Id-085D 11 Mar (089Ls) ω=261W

Id-086D 11 Mar (089Ls) ω=271W

Id-087D 11 Mar (089Ls) ω=281W

Mn-358D 12 Mar (090Ls) ω=216W

Mn-359D 12 Mar (090Ls) ω=226W

Mn-360D 12 Mar (090Ls) ω=236W

Mn-361D 12 Mar (090Ls) ω=245W

Mn-362D 12 Mar (090Ls) ω=255W

Mk-135D 12 Mar (090Ls) ω=260W

Id-088D 13 Mar (090Ls) ω=212W

Id-089D 13 Mar (090Ls) ω=222W

Id-090D 13 Mar (090Ls) ω=232W

 

where Mo=MORITA, and Mk=MURAKAMI.

  In the Mo image the afternoon Elysium is bright even though it was taken in Red. As seen from the example by MURAKAMI, Elysium this time proved most conspicuously whitish at ω=250W - ω=260W. The observations by Mn on 12 Mar was at Otsu, and Elysium Mons was detected at ω=226W.
  We have described mainly the trend of Elysium, but the region made of Cebrenia was also interestingly bright throughout the period.
  We also note that the afternoon Elysium shows the characteristic aspect in the Video images taken by HIGA (Hg) on 9 Mar, 10 Mar and 11 Mar. On 10 Mar at ω=218W, Elysium looks more whitish and brighter than Hellas. On the other hand the morning Elysium on the image on 15 Mar is not so whitish though bright.

  Elysium still faced to us. On 17 Mar (092Ls) at ω=192W, Elysium Mons was seen and the Elysium region of the morning was traced until 22 Mar. For example, in the observation:

Mk-141D 20 Mar (093Ls) ω=186W

the morning Elysium and Cebrenia were apparent.

  Elysium came into sight again in mid-April. The Y-shaped Elysium-Cebrenia region was still light. But the apparent diameter went down to 12 arcsecs, and we could not catch well the activity of Elysium Mons. On 23 Apr (108Ls) at ω=206W (Mn-554D), there were seen a few areas of bright spots inside Elysium, but looked somewhat off-white. Id also recorded on 20 Apr (107Ls) at ω=241W (Id-110D) that Elysium was off-white. A CCD Red image by AKUTSU (Ak) shows a light Elysium on 22 Apr at ω=235W.
  Around 20 Apr (107Ls), the morning Elysium and the following area showed a white-cloud burst as seen visually and as proved by the Video images by Hg as reported in Sketch (1) in No 197 (see also No 204). The cloud was thought as the one developed from the morning mist which covers frequently the morning Syrtis Mj to make it to be quite blue-greenish in this season.

  Finally we record an aspect of Elysium in Feb 1997 from the notes of the present writer: Elysium was visible from around 5 Feb (074Ls). Elysium and Cebrenia were light enough in a Y-shape, and on 7 Feb (075Ls) at ω=241W, there was seen an activity inside Elysium. On 8 Feb (076Ls) at ω=222W, Elysium was off-white yet, but at ω=242W more whitish than Cebrenia. On 10 Feb (076Ls) at ω=194W, Elysium was not white but at ω=233W became bright. The apparent diameter was less than

(Mn : Masatsugu MINAMI)


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